(1) Field of the Invention
The invention relates to a light source mechanism for an imaging apparatus, and more particularly to a combination which integrate a point light source with a light shield for producing a line light source with enhanced homogeneous illumination.
(2) Description of the Prior Art
An imaging apparatus or a scanner is one of popular computer peripherals. In an imaging apparatus, an internal light source is used to generate an image from a document rested upon a document plate. The image is then forwarded through a plurality of lenses and experiencing a proper travel path to reach a CCD for being transformed into digital signals. The digital signals are then sent to a computer for further image processing.
Referring now to FIG. 1A and FIG. 1B, a perspective and a side views of a conventional light source mechanism are shown, respectively. The light source mechanism 1 mainly comprises a fluorescent tube 12 and a light housing 14. The fluorescent tube 12 for providing illumination during an imaging process has a length substantially equal to the width of the document rested upon the document plate of the imaging apparatus. The light housing 14 provides a lengthy internal accommodation room 141 thereof for installing therein the fluorescent tube 12. The accommodation room 141 as shown includes a lengthy aperture 142 for allowing the light of the fluorescent tube 12 to pass therethrough. The inner surface of the light housing 14, formed as a reflection surface for collecting and reflecting the light to enhance the illumination of the light source mechanism 1, can be preferably embodied as an arc surface or a parabolic surface.
Nevertheless, the conventional light source mechanism 1 as discussed generally has several disadvantages as follows.
1. In the conventional light source mechanism, a fluorescent tube is usually used as the light source. Yet, it is well known that the fluorescent tube can only provide lights limited to a narrow wave length range, and generally within the range of visible lights. However, some imaging apparatus are designed to proceed the scanning by invisible lights. Under such an arrangement, it is obvious that the fluorescent tube cannot provide the required light source to perform the scanning.
2. The conventional fluorescent tube is generally a product of short-life term and is vulnerable to be broken as well as invaded by gas.
3. The illumination provided by the conventional fluorescent tube is sometimes unstable and consequently affects the scanning quality of the imaging apparatus.
4. The unit price of the conventional fluorescent tube is usually high, so that the cost of the imaging apparatus cannot be reduced to a competitive level.
To resolve the aforesaid disadvantages of the conventional imaging apparatus using the fluorescent tube as the light source, additional effort in the industry to develop an improved light source mechanism is definitely necessary for producing an imaging apparatus with low cost, long life term, quality performance and wide-ranged application.
Accordingly, it is a primary object of the present invention to provide a light source mechanism for an imaging mechanism, in which a point light source is applied to provide improved imaging quality and advantages of low cost, stable illumination, long life term and a wider application range.
The light source mechanism for an imaging apparatus in accordance with the present invention includes at least a point light source and a light shield. The light source of the present invention for the imaging apparatus to perform the document scanning, preferably includes two point light sources located respectively at both ends of the light shield. The light shield, having a shape of lengthy hollow pipe structure, provides an internal mounting element at each end thereof for installing thereinside the respective point light source. One feature of the present invention is that the light shield includes a long slot located along a longitudinal direction thereof for transforming the lights provided by the inside point light sources into a line light source for performing the illuminating of a document. In addition, the interior wall surface of the light shield is formed as a diffusion surface for evenly diffusing the lights emitted by the point light sources, and thus a homogeneous line light source can be provided through the long slot to perform the document illuminating.
According to the present invention, the diffusion surface inside the light shield can be formed by a plurality of ring protrusions. In theory of optics, the ring protrusion can provide even diffusion upon the incoming point light source, so that homogeneous line light source can be produced through the long slot, even though point light sources does be applied as the real light source inside the light shield. In the present invention, the lights emitted by the point light sources might travel a substantial period and experience several diffusion inside the light shield before leaving the light shield through the long slot, so that the light quality provided by the light source mechanism of the present invention can be better than that provided by the conventional light source; though two separate point light sources might be used inside the light shield of the present invention.
All these objects are achieved by the light source mechanism for an imaging apparatus machine described below.